• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 2003.05a
• /
• pp.673-677
• /
• 2003

$CO_2$ 의 배출로 인한 지구 온난화 진행을 막기 위하여 국제사회의 노력이 계속되고 있는 가운데, 일련의 기후변화 협약에 대한 기술적 대응수단으로써 $CO_2$ 저감 기술 확보의 중요성이 증대되고 있다. 우리나라도 향후 예상되는 $CO_2$ 배출 저감의무 부과에 대비하여야 할 것이며 발전부문과 같은 대규모 $CO_2$ 배출시설에서의 개선이 우선적으로 이루어져야 할 것이다.(중략)

• International Journal of Control, Automation, and Systems
• /
• v.6 no.4
• /
• pp.596-606
• /
• 2008

In this paper, we present a co-design methodology of dynamic optimal network-bandwidth allocation (ONBA) and adaptive control for networked control systems (NCSs) to optimize overall control performance and reduce total network-bandwidth usage. The proposed dynamic co-design strategy integrates adaptive feedback control with real-time scheduling. As part of this co-design methodology, a "closed-loop" ONBA algorithm for NCSs with communication constraints is presented. Network-bandwidth is dynamically assigned to each control loop according to the quality of performance (QoP) information of each control loop. As another part of the co-design methodology, a network quality of service (QoS)-adaptive control design approach is also presented. The idea is based on calculating new control values with reference to the network QoS parameters such as time delays and packet losses measured online. Simulation results show that this co-design approach significantly improves overall control performance and utilizes less bandwidth compared to static strategies.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2013.12a
• /
• pp.32-32
• /
• 2013

Using the Vienna ab initio simulation package (VASP) incorporating van der Waals interaction, we have explored structural, adsorption, and magnetic properties of Ni(111)/BN/Co(111) systems. We have found that both Ni(111) and Co(111) layers shows half metallic state, while the spacer BN layer becomes weak metal for one monolayer (ML) thickness and an insulating barrier for two ML thickness. The half metallic states in both Ni(111) and Co(111) layers are robust because it is unchanged independently on the magnetic coupling of Ni(111) and Co(111). This finding suggests that the Ni(111)/BN/Co(111) systems can be utilized for perfect tunneling magnetoresistance system. Moreover, it can be applied for potential spin injecting into semiconductor in FM/semiconductor system due to the fact that the half metallic state in FM layers at the interface will be unchanged.

• Proceedings of the KIEE Conference
• /
• 2003.07b
• /
• pp.1060-1062
• /
• 2003

In this study, an insulation design program which can calculate electric field of the GIS bus parts easily was developed. It also can evaluate the insulation safety depending on gas density. For bus parts of $1{\varphi}$ GIS, it was intended to provide a optimal diameter of a conductor and an enclosure automatically for the convenience of GIS insulation designer. This program was coded by Visual Basic and electric field was calculated by the Charge Simulation Method(CSM), which is one of the most accurate method for an electric field analysis.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.2496-2498
• /
• 2001

광 디스크 channel상에서 RSPC의 error correction capability를 확률적인 계산 방법으로 계산하는 데는 많은 어려움이 있다. 그 이유는 바로 광 디스크 channel이 burst error channel이기 때문인데, 이 burst error를 어떻게 다루는 가에 따라 그 error correction capability는 사뭇 달라진다. 이 논문에서는 Sony의 dust error distribution[1] 아래에서 4-state Morkov Chain[2]로 modeling하고 그 결과를 가지고 burst error를 channel의 특성과 ECC format의 특성에 맞게 제어할 수 있는 확률적인 계산방법을 소개하고 그것을 simulation하고자 한다.

• The Bulletin of The Korean Astronomical Society
• /
• v.43 no.2
• /
• pp.45.2-45.2
• /
• 2018

Twisted magnetic flux tubes (also called magnetic flux ropes) are believed to play a crucial role in solar eruptive phenomena. The evolution of a single flux rope with or without the influence of an overlying field of a simple geometry has been extensively studied and its physics is rather well understood. Observations show that interacting flux tubes are often involved in solar eruptions. It was Lau and Finn (1996) who intensively studied the interaction between two flux ropes, whose footpoints are anchored in two parallel planes. In this too simplified setting, the curvature of the flux rope axial fields is totally ignored. In our study, the footpoints of flux ropes are placed in a single plane containing a polarity inversion line as in the real solar active region. Our simulation study is performed for four cases: (1) co-axial field and co-axial current (co-helicity), (2) counter-axial field and co-axial current (counter-helicity), (3) co-axial field and counter-axial current (counter-helicity), and (4) counter-axial field and counter-axial current (co-helicity). Except case 3, each case is found to be related with certain eruptive features.

• Journal of the Korean Society for Heat Treatment
• /
• v.28 no.1
• /
• pp.24-31
• /
• 2015

In this study, a simulation was used to derive an optimal process of heat treatment with carburizing, and compared the derived result with SCr420HB helical gear in heat treatment with carburized quenching process about a change of the quenching method. The optimal carburizing process time is derived by the simulation with the theoretical time. The process has been performed by oil quenching and salt quenching method. Through the comparison of the results from the simulation(Hardness, effective case depth hardened by carburizing treatment and deformation) and the actual process, analyzed the error value of each quenching. And it verified the applicability of the simulation.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.1
• /
• pp.63-74
• /
• 2001

In this study, a cycle simulation program of a Unit-Injection(UI) system was developed to estimate the injection performance of newly designed injection system. A fundamental theory of the simulation program is based on the conservation law of mass. Loss of fuel mass in the system due to leakage, compressibility effect of the liquid fuel and friction loss in the control volume was considered in the algorithm f the program. For the evaluation of the simulation program developed, the experimental result which was offered by the Technical Research Center of Doowon Precision Industry Co. was incorporated. Two main parameters; the maximum pressure in the plunger chamber and total fuel mass(kg) injected into the engine cylinder per cycle, were measured and compared with the simulation results. It was found that the maximum error rate of the simulation result to the experimental output was less than 3% in the rated rotational speed (rpm) range of the plunger cam.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.74.2-74.2
• /
• 2011

A simulation study on synthesis gas process in GTL process was carried out in order to find optimum operation conditions for GTL (gas-to-liquid) pilot plant design. Optimum operating conditions for synthesis gas process were determined by changing reaction variables such as feed temperature and pressure. During the simulation, overall synthesis process was assumed to proceed under steady-state conditions. It was also assumed that physical properties of reaction medium were governed by RKS (Redlich-Kwong-Soave) equation. The effect of temperature and pressure on synthesis gas process $H_2$/CO ratio were mainly examined. Simulation results were also compared to experimental results to confirm the reliability of simulation model. Simulation results were reasonably well matched with experimental results.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.656-661
• /
• 2000

In the recent trend of electric power supply market, a variable pressure operation supercritical once-through steam generator is highlighted as a thermal power plant for cycling load because of its superiority in load regulation. Almost all thermal power plants of the future are expected to be variable pressure operation supercritical once-through units. APESS(Advanced Plant Engineering & Simulation System) is a dynamic simulation software for power plant which is under being developed by Korea Heavy Industries & Construction Co., Ltd. This paper present the introduction of APESS and the result of simulation for variable pressure operation supercritical once-through steam generator.